Title

Author

Document Type

Dissertation

Date of Degree

Spring 2016

Degree Name

PhD (Doctor of Philosophy)

Degree In

Geoscience

First Advisor

E. Arthur Bettis

Abstract

Portable X-ray fluorescence (pXRF) provides a new alternative to destructive methods of raw material characterization, such as X-ray fluorescence (XRF), neutron activation analysis (NAA), and traditional thin section petrography, although its effectiveness on coarse-grained materials, such as granite, has been questioned. This project addressed this question by determining the effectiveness of pXRF in characterizing granites from Belize and in sourcing granite ground stone tools from Maya sites in Belize. Geochemical fingerprints were defined for three potential source areas (granite plutons in the Maya Mountains of Belize) using outcrop samples. Samples were analyzed using pXRF, XRF, electron microprobe (EMPA), and thin section analyses. PXRF data from archaeological collections of granite ground stone tools from sites in Belize were then compared to the pluton geochemical signatures.

There were two principle results of this research. First, analyses indicated that pXRF can accurately characterize the geochemistry of granites from Belize on a suite of elements. Second, this research demonstrated that the Maya of Belize exploited multiple granite outcrops and participated in different kinds of exchange networks to acquire granite, sometimes acquiring stone from the nearest outcrops and sometimes not. While Mountain Pine Ridge was the dominant source outcrop that was exploited, Cockscomb Basin and Hummingbird Ridge granites were also quarried or scavenged. Sometimes the closest source was used, as is the case at Alabama, who exploited the locally available Cockscomb Basin granite. Through this study it appears that the nearest pluton was not always used. Instead Mountain Pine Ridge granite tools were imported from a greater distance, implying that there were additional factors, such as economic partners and changing political powers, which lead to Mountain Pine Ridge granite being the most pervasive in most archaeological collections within Belize.

Public Abstract

For centuries, the Maya of Belize have used stone tools to grind corn. Few researchers have analyzed where the rocks to make these tools were quarried. This work examines this issue by using portable X-ray fluorescence (pXRF) to develop fingerprints of the elements present in stone tools. This work examines the elemental composition of granite tools. Granite is the most abundant igneous rock in Belize, and a more suitable stone for grinding tools than softer sedimentary rocks. Portable X-ray fluorescence is a new technology that can analyze the elemental composition of a material without destroying it. With pXRF, it is possible to get an immediate elemental reading in the field without needing to damage the artifact.

This research determined that pXRF can develop chemical signatures that can be used to differentiate between different types of granite in the Maya Mountains. It is possible to identify potential exchange routes the Maya used from, production to discard. Results indicate that the majority of granite used for ground stone tools in Belize was obtained from Mountain Pine Ridge within the Maya Mountains. This was not always the closest pluton, indicating it had some cultural importance (e.g. political or economic partners) to the people who wanted to use these granite manos and metates. Granite from the other plutons was being exploited as well, but in much smaller quantities. It appears that the ancient Maya of Belize were actively choosing the granite from a specific area, even when it was not the most readily available.